I'm currently porting a D1 code base to D2 which has the following class hierarchy:

interface Map
{
     void clear ();
}

class Hashtable : Map
{
    synchronized void clear () {};
}

class HashMap : Map
{
    void clear () {};
}

When I compiler the code I get an error about the "clear" method in Hashtable not being covariant with the "clear" method in Map. Any suggestions how I could solve this, preferable working in D1 as well?

-- 
/Jacob Carlborg